1. Field of the Invention
The present invention relates to an aminoanthryl derivative-substituted pyrene compound, and to an organic light-emitting device using the compound.
2. Related Background Art
An organic light-emitting device is a device which includes a thin film containing a fluorescent organic compound between an anode and a cathode, which generates an exciton from the fluorescent compound by injection of an electron and an electron hole (hole) from each electrode, and which utilizes light to be radiated when the exciton returns to a ground state.
In a study conducted by Eastman Kodak Company in 1987 (Appl. Phys. Lett., 51, 913 (1987)), an anode formed of ITO, a cathode formed of a magnesium-silver alloy, and an electron transport material and a light-emitting material each formed of an aluminum quinolinol complex are used. Further, there is reported light emission of about 1,000 cd/m2 under application of a voltage of about 10 V from a device having a function-separated two-layer structure using a triphenylamine derivative as a hole transport material. Related patent documents include U.S. Pat. No. 4,539,507, U.S. Pat. No. 4,720,432, and U.S. Pat. No. 4,885,211.
Further, light emission in ultraviolet to infrared regions is possible by changing the type of fluorescent organic compound. Recently, various compounds have been studied actively (U.S. Pat. No. 5,151,629, U.S. Pat. No. 5,409,783, U.S. Pat. No. 5,382,477, Japanese Patent Application Laid-Open No. H02-247278, Japanese Patent Application Laid-Open No. H03-255190, Japanese Patent Application Laid-Open No. H05-202356, Japanese Patent Application Laid-Open No. H09-202878, and Japanese Patent Application Laid-Open No. H09-227576).
In addition to the organic light-emitting device using a low molecular weight material as described above, an organic light-emitting device using a conjugated polymer has been reported by a group of Cambridge University (Nature, 347, 539 (1990)). In this report, light emission has been confirmed from a single layer of polyphenylene vinylene (PPV) formed in a coating system. Patents related to an organic light-emitting device using a conjugated polymer include U.S. Pat. No. 5,247,190, U.S. Pat. No. 5,514,878, U.S. Pat. No. 5,672,678, Japanese Patent Application Laid-Open No. H04-145192, and Japanese Patent Application Laid-Open No. H05-247460.
Recently, an organic phosphorescence device using an iridium complex such as Ir(ppy)3 as a light-emitting material has attracted attention and its high luminous efficiency has been reported (Appl. Phys. Lett., 75, 4 (1999)).
Recent advances in organic light-emitting device are remarkable and characteristics of the organic light-emitting device allow formation of a thin and lightweight light-emitting device with high luminance under application of a low voltage, wide range of emission wavelengths, and high-speed response, thereby suggesting the possibility of extensive uses. However, the organic light-emitting device still has many problems in durability such as change over long-term use, and degradation by an atmospheric gas containing oxygen, by moisture, and the like. For application of the organic light-emitting device to a full-color display or the like, blue, green, and red light emissions with extended-life, high conversion efficiency, and high color purity are required under the present circumstances, and various proposals have been made.
An example of a material containing an anthracene ring used for an organic light-emitting device is a phenylanthracene derivative disclosed in Japanese Patent Application Laid-Open No. H08-012600. In particular, use of a phenylanthracene derivative as a blue light-emitting material or an electron-injection transporting material allows formation of a favorable organic film because of low crystallinity of the phenylanthracene derivative. However, the phenylanthracene derivative has insufficient luminous efficiency and durable life for practical use.
Japanese Patent Application Laid-Open No. H09-157643 and Japanese Patent Application Laid-Open No. H10-072579 disclose an aminoanthracene derivative and a diaminoanthracene derivative, respectively. Those materials are used as light-emitting materials and allow green light emission. However, devices produced by using those materials each have low luminous efficiency and insufficient durable life for practical use.
Japanese Patent No. 3008897 discloses a device using a specific bianthryl compound as a light-emitting material, which allows light emission with high luminance. However, the patent document includes no description of luminous efficiency or durable life.
Japanese Patent Application Laid-Open No. H11-008068 discloses a device using a specific anthracene compound containing an olefin site as a light-emitting material, which allows yellow to red light emissions. However, the device has insufficient luminous efficiency for practical use.
Japanese Patent Application Laid-Open No. 2001-284050 discloses a device containing an anthracene derivative with a specific structure, an electron transport compound, and another fluorescent compound in a light-emitting medium layer, to thereby provide a red light-emitting device with improved reliability. However, the device has insufficient luminous efficiency for practical use, and blue light emission is hardly observed because of a device structure.
Japanese Patent Application Laid-Open No. 2002-324678 discloses an example of a material containing pyrene substituted into a benzene ring used for an organic light-emitting device, to thereby provide a device with favorable luminous properties and durability. However, the device has low external quantum efficiency, and the patent document includes no specific description of durable life.